In many manufacturing environments, it is necessary to visually inspect articles being assembled to detect surface defects. In the automotive industry, inspection areas are located along the assembly line so that assembled automobiles can be inspected for surface defects such as for example dirt, sags, dents, dings, fisheyes, scratches, mottle, orange peel etc.
To facilitate visual inspection of the automobile coated surfaces, the inspection areas include rows of fluorescent luminaires installed above and/or on opposite sides of the assembly line. The luminaires are equipped with various types of fluorescent lamps including high output (HO) or very high output (VHO) fluorescent lamps. As the automobiles travel along the assembly line and pass through the inspection area they are illuminated and the images of luminaire lenses and fluorescent lamps are reflected by the specular surfaces. The recommended illumination is at least 200 foot-candles (fd). In many instances the illumination is well above this level.
Inspection personnel detect defects by viewing the specular surfaces from various angles depending on the relative position of the reflected images and the position of inspection personnel. Arranging conventional luminaires to achieve the desired illuminance creates many problems. In particular, the illuminance level results in discomfort and disability glare causing inspection personnel to suffer eye fatigue, headaches and/or migraines. Also, inspection personnel must constantly bob and weave to see visual defects in the distorted luminaire lens images reflected by the specular surfaces thereby increasing the risk of back pain.
To reduce glare, baked enamel high reflectance reflectors with prismatic lenses have been used in the luminaires. Unfortunately, the images reflected by these luminaires onto the specular surfaces of the automobiles being inspected include images of the reflectors and lenses with images of the fluorescent lamps superimposed thereon. The resulting reflected images are distorted and unclear making it more difficult for inspection personnel to detect surface defects.
Specular lenses have also been used in luminaires with clear lenses and without lenses in the luminaire. Although the reflected images are apparent they are not sharp due to contamination which rapidly decreases reflectivity resulting in blurred images. As well, the highly specular reflective material tends to bend and flex easily resulting in distortion of the reflected images and creating secondary vague images.
In addition to the above problems, conventional luminaries have typically consumed significant amounts of power, much of which is converted into heat. This heat dissipation has resulted in an increase in fluorescent lamp temperature which reduces the light output of the fluorescent lamp. As will be appreciated, improved luminaires for facilitating the visual inspection of articles to detect surface defects are desired.
It is therefore an object of the present invention to provide a novel inspection area and a luminaire for the same.